Kratom and Other Mitragynines: The Chemistry and Pharmacology of Opioids ... - Google Books

https://books.google.de/books?id=BtPMBQAAQBAJ&pg=PA152&dq=Thiambutenes+Diethylthiambutene&hl=de&sa=X&ved=0ahUKEwibuZm13_DNAhVpJJ

Opioids such as morphine, codeine, and oxycodone are extracts or analogs isolated from a single source: the opium poppy. For a long time, it was believed to be nature’s only source of opioids. But it now appears that biological diversity has evolved an…